[BUG] Slash command are now executed with the task tool, this is a problem for interactive prompts

Environment

• Platform (select one):
• [X] Anthropic API
• [ ] AWS Bedrock
• [ ] Google Vertex AI
• [ ] Other: <!-- specify -->
• Claude CLI version: 1.0.63 (Claude Code)
• Operating System: Windows 11
• Terminal: Windows Terminal

Bug Description

When running a slash command, by default Claude Code runs it using a task tool, example below. This is not desirable with prompts that are designed to be interactive.

Steps to Reproduce

1. Start a slash command using /prompt-file

Expected Behavior

The prompt should execute interactively

Actual Behavior

The prompt is executed hidden using the Task tool

Additional Context

Example:

> /start-next-task-card is running…

✻ Thinking…

  The user is running a /start-next-task-card command which is a custom slash command. According to my instructions, when I'm instructed to execute
  custom slash commands, I should use the Task tool with the slash command invocation as the entire prompt.

  Let me use the Task tool to execute this slash command.

● I'll execute the /start-next-task-card command for you.

● Task(Execute start-next-task-card command)
  ⎿  Initializing…
  ⎿  No (tell Claude what to do differently)

> Where in your instructions says you  should use the Task tool with the slash command invocation as the entire prompt? In what file?

✻ Thinking…

  The user is asking where in my instructions it says I should use the Task tool with the slash command invocation as the entire prompt, and in what
  file this instruction appears.

  Let me look through my instructions to find this specific guidance.

  Looking through my system message, I can see this instruction:

  "A custom slash command is a prompt that starts with / to run an expanded prompt saved as a Markdown file, like /compact. If you are instructed to
  execute one, use the Task tool with the slash command invocation as the entire prompt. Slash commands can take arguments; defer to user
  instructions."

  This appears in the "Tool usage policy" section of my system instructions, not in any file that the user provided.

● Looking at my system instructions, this guidance is in the "Tool usage policy" section:

  A custom slash command is a prompt that starts with / to run an expanded prompt saved as a Markdown file, like /compact. If you are instructed to
  execute one, use the Task tool with the slash command invocation as the entire prompt. Slash commands can take arguments; defer to user
  instructions.

  This instruction is part of my core system message, not from a user-provided file.